1. Field of the Invention
The present invention relates to a semiconductor device having a shielding layer.
2. Description of the Related Art
A semiconductor device package called a Chip Size Package (hereinafter, called CSP) is similar in size to a semiconductor chip. A type of CSP is called a wafer level chip size package (Wafer Level Chip Size Package: WCSP) or wafer level chip scale package (Wafer Level Chip Scale Package: WCSP).
The conventional WCSP type semiconductor device has electrode pads formed on a semiconductor chip and an insulating layer formed on the semiconductor chip. The insulating layer has openings and the electrode pads are exposed through the openings. The WCSP also has external terminals formed on the insulating layer and redistribution wirings formed on the insulating layer. One end of the redistribution wirings is connected to the electrode pads via the openings and the other end of the redistributions is connected to the external terminals.
The semiconductor chip of the WCSP includes a semiconductor substrate and a circuit element. The circuit element includes electric elements formed on the semiconductor substrate and a multilevel interconnections.
The insulating layer and the redistribution wirings are sealed by a sealing resin. The external terminals is exposed from the sealing resin.
In the fabrication of the WCSP type semiconductor device, each of semiconductor devices is separated or diced after the sealing resin is formed on the wafer.
In the conventional WCSP type semiconductor device, the insulating layer that is formed between the redistribution wirings and the electric circuit is very thin. Therefore, the circuit element might be affected by a noise from the redistribution wirings. If the semiconductor device has a capacitor or an analog circuit, a capacitance value or a waveform characteristic in the analog circuit might be changed in response to the noise.
A semiconductor device that has an improved noise shielding feature has been described in Japanese Patent Laid-Open No. 2000-235979. The semiconductor device disclosed in this reference has a ground layer which is formed between the semiconductor chip and the redistribution wirings.
However, an additional process for forming the ground layer is needed in the semiconductor device disclosed in the reference. Also, the ground layer increases a thickness of the semiconductor device.